An authentication prompt is received in Outlook even though a user is successfully authenticated in Forefront Unified Access Gateway 2010

Symptoms

After Service Pack 2 is applied to the server that is running Microsoft Forefront Unified Access Gateway 2010, a Microsoft Outlook user successfully authenticates with that server to access Outlook Anywhere. If the user is not in the list of authorized users for the application, Forefront Unified Access Gateway returns an authentication prompt even though the user is successfully authenticated.

In this case, when a user is not in the list of authorized users, you would expect Forefront Unified Access Gateway to return an error to Outlook and Outlook to enter a disconnected state.

Cause

This problem occurs because Service Pack 2 introduced an unexpected change in behavior.